Flow meter



Nov. .19, 1940. E. l.. FISCHER 2,221,943

FLow METER Filed July 5, 193B I5 Sheets-Sheet 2 /IlIIIIl/lllllllllllf'/23 HHHHHl-l HIHHIIIIIIIH [fw/miran' Y Nw. 19, 1940. V E L, HSCHERA2,221,942'.

FLow METER Filed July 5, 1958 3 Sheets-*Shed 3 Patented Nov. 1-9, 1940UNITED STATES PATENT OFFICE FLOW METER Edward L. Fischer, Davenport,Iowa Application July 5, 1938 Serial No. 217,356

. 6 Claims.

The present invention relates to flow meters,

particularly of the type for the metering of gaseousor vaporoussubstances such as natural gas, manufactured gas, steam, air or anyother substances in vapor phase flowing through pipes or conduits.

One of the objects of the invention is to provide an improved flow meterwhich will register the amount of such gaseous material flowing in apipeor conduit, in terms of (1) the weight of i such materiaLor (2) thevolume of such material at flowing conditions, or (3) the volume of suchmaterial corrected to any stated conditions of pressure and temperature,whichever may be required. Another object of the invention is to'provide an improved flow meter which does not require any outside sourceof electrical energy or other power. In-such improved construction,electrical energy -is utilized in the performance of certain controlfunctions, and, in several embodiments of the in- A vention, electricalenergy is also utilized for the transmission of power between theoperating parts. However, such electrical energy is generated directlyin the meter apparatus, and hence there is no necessity for maintainingbatteries at the meter location, nor of running a power supply linethereto.

Other objects and advantages of the .invention will be apparent from thefollowing detail description of certain preferred embodiments thereof.

In the accompanying drawings illustrating such embodiments:

Figure 1 is a diagrammatic representation of one embodiment;

Figure 2 is a transverse sectional view taken approximately on the planeof the line 2- 2 of Figure 1;

Figure 3 is a fragmentary sectional view diagrammatically illustratinganother embodiment of density responsive device which I may employ;

Figure 4Y is a diagrammatic representation ot another embodiment of theinvention;

Figures 5, 6 and '7 are diagrammatic views showing other means forimparting the kinetic energy of the fluid to the generator or rotary`member.

Referring to Figure 1, a section of the conduit through which the fluidflows is indicated at II, the direction of fiowtherethrough beingdesignated by the arrow .'c, The conduit -section Il may be a speciallyconstructed section adapted to have certain parts of the meteringapparatus (Cl. 'I3-230) mounted thereon or associated therewith, thisspecially constructed section being interposed in the run of the conduitand being coupled to the contiguous end portions IIa and IIb by thecoupling anges I2, I2 and I3, I3. Rigidly secured to the side, top orbottom of the conduit II is a housing I in which is mounted an impactwheel I6. This wheel comprises four or more vanes Il which preferablyextend substantially radially from a central hub which is mounted on ashaft I8. The vanes revolve through a. slot I9 cut 1ongitudinally intheconduit II, whereby the fluid flow impacts against the vanes andcauses their rotation. 4As shown in Figure 2, the tips of the vanesreach substantially to the center of the conduit II so that the vanesrespond to an average. of the iiow velocities at different radii of theconduit. In this regard, the sector shaped 'profile of the vanes is inaccordance with the teaching of my prior Patent No. 2,082,539 issuedJune 1, 1937. Also, if desired, the opposite edges of each vane may becurved in accordance with the teachingof said Patent No. 2,082,539. Theshaft I8 may be supported in bearings carried by the housing I5 or inbearings carried by the generator 21, or both, the upper bearing 2|representing an anti-friction or jewel bearing carried by the housing,which may be duplicated at the lower end of the shaft, if desired. Thefront of the housing I5 is provided with a marginal flange 23 to which aremovable cover plate 24 is secured by screws or bolts, a gasket 25being interposed between the flange and cover plate to insure apressure-tight enclosure. 'I'he inner portion of the housing I5 may bebolted to the conduit II, or the'housing may be welded to or castintegral with the conduit'to minimize the possibility of leaks. The

generator 2l is mounted on or otherwise driven by the shaft I 8, andispreferably in the form of mounted on the stator. When-the windings areY mllllted Qn the rotor, current connection therefrom an outside sourceof current supply, but in keeping with the object of my invention toavoid the necessity of such outside source of current supply, I proposeusing a permanent magnet field, this being embodied in the form of astator 29 when the windings are mounted on the rotor 28. The conductors3|, 32 and 33 for the three phase circuit are extended out of thehousing I through insulating bushings 34, and the conductors 35 and 35of the single phase circuit are extended out of the housing throughinsulating bushings 31, whereby the housing may be maintained gas-tight.

The indicator or register which integrates the flow over a period oftime can be mounted in close proximity 'to the housing I5, or can Ibelocated a substantial distance therefrom. This apparatus is enclosedwithin a separate gas-tight housing 4I which is provided with a frontmarginal flange 42 to which a removable front cover 43 is secured inmuch the same manner as described above in connection with the housingI5. Enclosed within this housing is a rotary member m on which thevarious driving and braking forces are imposed in the controlledoperation of the system. This rotary member is typically represented bya shaft having precision, antifriction mounting in bearings 44,'44carried by the opposite end walls of the housing 4 I. The rotation ofsaid shaft actuates integrating counters or dials 45 of any conventionaltype, these integrating devices being enclosed within the housing 4I andbeing visible through a glass covered sight window in the cover plate43.-

Mounted on or operatively connected with thev shaft m, within thehousing 4 I, is an electric motor 41 serving to drive the shaft. Whenthe generator 21 is a three phase alternator, the motor 41 is preferablya three phase synchronous motor. Here again, the three phase windingsmay be mounted either on the rotor 48 Aor on the stator 49, althoughthey are preferably mounted on the rotor, in which case the rotor hascon-Y ventional slip rings as shown for connection with said windings.Likewise, the leld is preferably a permanent magnet structure to avoidthe necessity of external excitation, this permanent magnet structurepreferably constituting the stator 49. The three phase conductors 3|, 32and 33 enter the gas-tight housing 4I- through insulating bushings 5Ifor connection with the rotor windings. By having an identical orrelated arrangement of windings, salient poles etc. in the alternator 21and in the synchronous motor 41, an electrically synchronized relationis established which causes the motor to run at the same speed as thealternator or at some xed speed ratio thereto. nized relation issubstantially equivalent t`o a direct mechanical drive between thedriving shaft I8 and driven shaft m, insofar as the ability to transmittorque or load in either direction is concerned. That is to say, one ofthe fundamental features of the present system is the step of imposing acontrollable braking retardation or counter torque on the driven shaft min the performance of one of the control functions, and when suchbraking retardation is increased for reducing the speed of said drivenshaft this speed retarding eiect is transmitted back through theelectrically synchronized m0- tion transmitting'parts to slow down. thespeed of the driving shaft I8 substantially proportionally ly at 53.

This electrically synchrowith is established through conventional supyrings, as shown. Field excitation may be effected to the reduction ofspeed of the driven shaft m.

The controllable braking retardation or counter torque which is imposedon the rotary memb`er m may be effected by any suitable short circuitedgenerator or like device, indicated general- In the preferred embodimentillustrated I employ a Faraday disk 54 which is secured to the rotarymem-ber m. and which is responslve to a damping electromagnet 55. Saidelectromagnet has poles disposed on opposite sides of the disk 54, andincludes a winding 56 which'is adapted to be energized by the-singlephase current supplied through the conductors 35 and 36.- It will beunderstood that increasing and decreasing the current ow through the ywinding 56 increases and decreases the counter torque or retardationimposed on the rotary member m through the disk 54.

In the embodiment of the invention illustrated in Figure 1, suchincrease and decrease of current flow is 'arranged to be inverselyresponsive the conduit Il, the provision of the two pipes serving tomaintain a small degree of circulation' through the closed chamber andinsuring 'that the density of the gas therein is -the same as thedensity of the gas in the conduit I-I. Within. the closed casing 59 is alarge, hollow, hermetically sealed chamber 68 which is of light, rigidmaterial, the diagrammatic illustration thereof in Figure 1 representingeither a sphere or one end of a relatively long cylinder. The weight ofthis chamber 68 is sustained by mercury displacement in an upper contactchamber 69 so that the cham-ber 68 is gas buoyant and hence rises andfalls with varying gas densities in the casing 59. Secured to the upperside of the kbuoyant chamber 68 is a light cage comprising a pluralityof spaced upwardly extending arms 1I which have attachment at theirupperl ends to a disk or spider 12. A displacement plunger 13 extendsdownwardly from this disk or spider into a quantity of mercury 'I4contained within the mercury cup 69. Said mercury cup is stationarilysupported by a bracket 'I5 extending outwardly therefrom between thecage arms 1I and having attachment to the casing 59. The verticallymovable assembly 68, 1l, 1.2 and-13 is guided by a guide pin 'I6extending downwardly from the buoyant chamber 68 and sliding within astationary guide 11, and by an upper guide pin 18 extending upwardlyfrom the disk or spider 12 and sliding within a guide strut or` spider19 which may be clamped between the flanges 63 and 64. The mercury cup69 is composed of suitable insulating material, and embedded in the.

. 35 and 11 enter'the casing through insulating bushings 83 and connectwith the upper and lower ends of the resistor 82, or withupper and lowerand connects through a pipe 81 with-the gas concontacts 8|, or with bothsaid contacts and the resistor. l

The parts are so proportioned that when the gas within` the casing 59 isat a predetermined minimum density or low density, compared to aselected standard of density, the buoyant chamber 68 will movedownwardly substantially to its lowermost position,`thereby lowering thedisplacement plunger13 to its maximum depth within the cup 69, causingthe mercury 14 to riseand make contact with substantially all of thecontacts, whereby all or the major portion of the resistance value ofresistor 82 is shunted out of circuit so that a relatively large currentflow passes through the winding 56 on the electromagnet 55. The greaterflux density thereby caused to thread through this electromagnet andthrough the retarding disk 54 interacts with the increased currentgenerated in said disk to impose a greater braking retardation orcounter torque on the rotary member m, thereby resulting in a slowerrate of integration at the dials 45, corresponding to the lower densityof the gas. Conversely, when the density of the gas within the casing 59rises to a predetermined maximum or highvalue relatively to this samestandard of density, the buoyant chamber 68 moves upwardly and withdrawsa substantial portion of the displacement plunger 13 from the mercurycup 69 so that the mercury level therein falls toits lowest point andbreaks contact with all or most of the contacts 8|. This interposes allor most of the resistance of element 82 in series with the winding 56 sothat the current ow therethrough is reduced. Consequently, less brakingretardation or counter torque is imposed on the rotary member m, andaccordingly the integrating dials 45 are advanced more rapidly,corresponding to the increased density of the gas flowing vthrough theconduit The spacing of the contacts 8| in the mercury cup 69 or thespacing of the taps which lead from the resistor 82 to these contactsmay be varied as desired to give a straight line variation in thetotalizing integration proportionately to change in density of the gas,or to give any other desired variation in the integration. The speedchanges which are thus exercised over the rotary member m by changes inthe density of the gas are transmitted back as load variations to thealternator 21 so that the speed of this alternator and of the vane'wheelI6 varies substantially proportionately therewith.

Small losses are likely to arise in the system as thus far described,due to reduction in driving torque by reason of vane speed, alsoretarding torque caused .by friction, windage, etc., also voltage dropin the alternator 21 due to the current drawn from it to operate thesynchronous motor 41 and to energize the winding 56 of the electromagnet55, and also the effect of any voltage generation in said coil 56 by theaction of current ow in the disk 54. These losses, while small comparedto the driving torque, may become, especially at light loads, sufficientto cause inaccuracies which might be regarded as objectionable in 4someinstallations. Accordingly, I have devised improved means forcompensating for these losses, which may be incorporated in theapparatus, if desired. This compensating means comprises an impulsewheel 85 which is mounted on or connected with the rotary member m, saidwheel comprising peripheral vanes or pockets against which a jet of themeasured gas or other uid is discharged through a nozzle 86. The nozzle86 extends through the wall of the casing 4| -phragm plate 93.

- nator 21.

conventionally indicated at |88, this meter alsoA duit After the gas hasimpinged against the impulse wheel 85, it is returned from the housing.4| back to conduit section ||b through pipe` 88. A control device,preferably in the form of a needle valve 89, is interposed in the pipe81 for controlling the ow of gas to the impulse wheel. Suitable means isdisposed in the gas'conduit to establish a pressure differential betweenthe points of communication of the pipes 81 and 88 with said conduit. Ipreferably employ a spring pressed valve 9| adapted to restrict the flowof the gas through a valve port 92 formed in a dia- This assembly can beconveniently mounted in the gas conduit by clamping the edge of thediaphragm plate 93 between the coupling flanges |3 which connect theconduit sections and ||b. Rods 94 projecting posteriorly from thediaphragm plate have threaded rear ends for receiving nuts 95 whichadjustably support the strut or spider 96. 'Ihe valve 9| is mounted on'a stem 91 which is slidably guided at one end in said strut or spider,and which is guided at its other end in the hub of a spider 98 which is-secured to the front side of the diaphragm plate 93. 'A compressionspring 99 is mounted on the stem 91 between the valve 9| and the strut96, and by screwing the nutsI 95 backwardly or forwardly said strut canbe shifted to adjust the pressure of said spring 99. By appropriatelyadjusting the positionspf these nuts, and by adjusting the setting ofthe needle valve 89, any desired rate of flow of gas impinging againstthe impulse wheel 85 may be obtained to afford'any desired degree ofcompensation. The yieldable mounting of the valve 9| accommodateschanges of velocity of the gas within the conduit.

The gasflow through the conduit can be indicated or registered at aremote point by the transmission of electrical' energy from thegenerator 21 to al remote indicating or registering device. A remoteregister is diagrammatically indicated at |8|, the la'tter comprisingthe conventional series of integrating dials or counters |82 which arearranged to be driven by an alternating current motor |63. The motor maybe a three phase synchronous motor connected to the three phase circuits3|, 82 and 33, although a small, self-starting single phase motor, ofthe 35, 36, or might even be energized by a separate winding on thealternator 21. A direct reading indication of the rate of gas flow atany time can also be given through remotely located indicatorsresponsive either to voltage or frequency.

A meter responsive to voltage is indicated at |01,

this meter being connectedto the branch circuit |84, |85, and being anysuitable type of volt meter calibrated to indicate the rate of gas flowin terms of the Voltage generated bythe alter- A meter responsive tofrequency is being energized through the remote indicating circuit |84,|85, and being calibrated to indicate `the rate of `gas iiow in terms ofthe frequency `ment illustrated in Figure 1, gas flowing-through theconduit ||l strikes against the vanes |1 with a force proportional tothe product of the density d of the gas and the square of its velocity v(neglecting for the moment the speed of movement of the vanes). Sincethese vanes are mounted on a shaft I8 which is free to rotate, suchforce creates a torque Tg on generator shaft I8 proportional to dez, andthe: resulting rotation of the rotor 28 induces an electromotive forcein E in the windings of the alternator 21. Since the ux set up by thepermanent magnet is constant, the voltage E will be proportional to thespeed of rotation Sg of the generator shaft I8. The voltage E will causea current ow through the windings of synchronous motor 41, whichcurrentwill exert a torque Tm on the rotor 48 of thesynchronous motor, causingit to rotate for driving the integrating dials and also driving the disk54. The single phase Winding in the alternator 21 will establish avoltage in the control circuit 35, 36 which will remain equal orproportional to the voltage E established Bin the three phase circuit3|, 32 and 33 during different speed changes of the alternator. lThisvoltage in the control circuit will cause current to flow throughresistor 82, contacts 8|, mercury 14, and the winding 56 on theelectromagnet 55. The current through this winding of the electromagnetwill cause the magnetic flux F to pass from pole to.po1e through thedisk 54, and this flux will induce current iiowin the disk 54 which-willin turn-react with the flux to cause.- a counter torque or brakingretardation Tr to :be exerted on disk 54, opposite to its motion. It isWell known in the art that the torque Tr exerted on disk 5,4 in adirection opposite to its motion is a function of the product of thefiux'F and the motor speed Sm. The flux F created in the `electromagnet55 is proportional to the current I flowing through the winding 56 ofsaid electromagnet. The retarding torque Tr then is proportional to theproduct of current I through the .winding 56 of the electromagnet 55 andthe speed Sm of shaft m, i. e.; Tr=KSmI (K representing a constant).

The current I, assuming the impedance of the circuit constant andneglecting for the moment any electromotive force that may be generatedin the winding 56 of the electromagnet 55 by the action of the currentnow in the disk 54, will be proportional to the voltage E. As previouslymentioned, the voltage E is proportional to the speed Sg of thegenerator 21.

Since the speed of the synchronous motor 41 must be proportional to thespeed of the generator 21, or equal to the speed of the generator ifboth have the same number of poles, then Sg is proportional to Snr, andthe torque Tr becomes proportional to the square of speed Sm. This maybe seen more clearly by tracing through the following mathematicalequations in which K, K1, K2, etc., represent constants applicable todiierent portions or operations of the apparatus:

(1) Tr=KSmF but (2) F=K1I Substituting K11 for F in (l) (3) TT=K K1 SmIbut (4) I=K2E (assuming constant impedance) Substituting KzE for I in(3) (5) Tr=K Ifll'fZnS'mE but (6) E=K3Sgv Substituting for E in (5)T1=`K KIKZKSSmSg but (8) Sg=K4Sm locity v becomes proportional to thesquare of the speed Sm, or expressed as an equation:

Therefore, if d be constant, that is if the gaseous material is ofunchanging composition and unvarying as to pressure and temperature, thesquare root of d is constant and the speed Sm becomes proportional tothe velocity v or, inasmuch as the area of the conduit is constant,proportional to the rate of flow or volume of ow per unit time and,hence, each revolution of rotary member m represents a given volume ofthe.

owing gaseous material. Therefore, by proper proportioning of the gearratio of the index' or integrating device 45 such index or integratingdevice may be caused to indicate the volume of gaseous material passedduring any period of time.

If the density of the flowing gaseous material be not constant butvarying from time to time, the speed Sm of rotary member m will vary inproportion to the square root of such changes unless the function of thedensity responsive device 58 be introduced as a correcting factor, i.e., unless the current I in the winding 56 of electromagnet 55 be variedin such a way as to be proportional or inversely proportional to thedensity. As previously described, the gaseous material flowing inconduit II is lead into and outof casing 59 through pipes 65 and 66, andis therefore present at all times in casing 59 at density d. There willtherefore be exerted on closed chamber 68 a buoyancy tending to liftvthis chamber and its attached parts against the action of gravity. Thisforce of buoyancy will be at all times proportional to the-density ofthe gaseous material. The net downward force will therefore decrease asthe density increases, thus requiring less mercury displacement to floatthe chamber 68 and its attachi ments, and hence the chamber will risesufficiently so that the weight of mercury displaced by displacementplunger 13 will again be equal to the net downward force on chamber 68and its attached parts. As the plunger 13 rises the level of the mercury14-in cup 69 falls, and if plunger 13 and cup 69 be of uniform crosssection the fall in mercury level will be proportional to the increasein density of the gaseous material. Similarly, if the density bereduced, the mercury level will rise. The mercury level will thereforebe inversely proportional to the `change in density. By suitablearrangement of the contacts 8l and their tapped points of connectionwith the resistor 82, the impedance of the circuit of the coil 56 of theelectromagnet 55 may be varied directly proportional to the level ofmercury in the cup 469. Since the level of mercury in this cup isinversely proportional to the densityV d of the gaseous material, theimpedance of the electhe product of density d and the square ofvetromagnet coil circuit may thereby be made to vary directlyproportional to the density d. Assuming contacts 8| and their tappedpoints of connection with resistor 82 to be arranged in the abovedescribed manner so as to cause the impedance Z of the coil circuit ofelectromagnet 55 to vary directly with the density d, .then current Ibecomes equal to voltage E divided by impedance Z, or proportional to Edivided by d, that is inversely proportional to d.

Thus

Substituting this value of I in Equation (3) above We have (14)TY=KK1I2SmE Substituting this value of E from Equation (6) (15)Tr=KK1K2dK3SS,

or since Sg Kgs," i

2 (16) TFKKlXzfsKiSm 2 (17) :PF-Kfm but 18) Tf=Ti and since du2 n (19)Ta= we have dv2 K5S,2 (20) Iz-T and 192 d 2v2 (21) Sm2=-K"X5-g-Ksdzv2(22) Sm K7dv The speed is therefore proportional l to the product ofdensity d and velocity v or, since the area of conduit Il is constant,the speed is proportional to the product of density and volume of flow,which means that it is proportional to the Weight or mass of gas flow.Each revolution of shaft m will therefore represent a definite weight ofgaseous material flowing in conduit Il, and the index Ior counter 45with proper gear ratio may be calibrated to represent the Weight of gaspassed during a given period.

For gaseous materialof constant composition,V a given volume of such gasat a stated pressure and temperature will have a definite weight. If,therefore, it is desired to ascertain the volume of gaseous materialpassing through conduit Il, corrected to a given pressure andtemperature condition,'the gear ratio of the index device 45 may be madesuch that it will so register.

If it is desired to measure the actual volume of flow at owingconditions of a iiuid of changing density, then the density responsivedevice Within the casing 59 would be modified to have a reversedoperating relation, as indicated at 58 in Figure 3. In this arrangement,the gas buoyant chamber 58' is pivotally suspended from one vincreasedgas density and fall with decreased gas density, thus causing theimpedance ofthe circuit to vary inversely with the density, with theresult that the current in the circuit will vary directly with thedensity. Under these conditions, the retarding or counter torque Tr willbe proportional to the product of the square of the speed and the firstpower of the density,

Y thusz" Neglecting losses, the driving torque (i112 is eque. totheretarding torque Smzd, thus:

(24) Kldv2 KSmZd whence (25) SM2 liga or smi Kw2 whence S5., Kav

The ,speed S is therefore proportional to the velocity v, or since thearea of conduit I I is constant, the speed is proportional to the volumeof iiow. Each revolution of shaft m will therefore represent a definitevolume of gas ow at flowing conditions, and the index or counter 45 withproper gear ratio may be calibrated to represent the volume ofvgaspassed during a given period.

All of the above explanation and discussion has neglected any reductionin driving torque by reason of vane speed, any retarding torque causedby friction, windage, etc., any voltage drop in the alternator 21 due tothe current drawn from it to operate the synchronous motor 41 and theelectromagnet 53, and also the effects of any voltage generation in thecoil 56 of said elec-` less some means of compensation is provided.

Considering these effects in the order above mentioned:

v(1) vLoss of driving torque by reason of motion of the impact 'DanesThe speed of motion of the vanes l1 will reduce the applied drivingtorque below the value that would be effective on a single stationaryvane extending at right angles to the gas flow, this being evident fromthe fact that the torque or force is a result of the relative velocitiesbetween the gas and the vane. Accordingly, in the preferred embodimentsof my invention herein disclosed, the vane speed is preferably kept lo-wrelative to the gas velocities, so that the driving torque 4will beaifected by the vane speed as little as possible. Such reduction indriving torque will be proportional tothe speed.

(2') Friction The retarding torque due to friction, assuming uniformbearing conditions, will be approximately proportional to the speed.

Cil

(3) Windage z The windage will be small but whatever it is it will varyin proportion to the square of the speed.

(4) Voltage drop in the generator Since the resistance of the generatorwindings (neglecting temperature rise) will be constant, the voltagedrop in the generator windings will be directly proportional to thecurrent supplied by the generator. The current thus supplied mustprovide the driving torque for shaft m through the instrumentality ofthe synchronous motor 41, and must also energize the coil 58' oi theelectromagnet 53. The load on the synchronous motor41 is primarilycaused by the retarding torque Tr and is therefore proportional to thesquare of the speed. The current through coil 56 of the electromagnet 53is, except for changes in density, proportional to the speed. Thecurrent supplied by the generator then is proportional to some functionof the speed Sg or Sm greater than the first power but less than thesquare. n Voltage generation by currents in disc 54 aecting flux fromcore 55 of electromagnet 53 'I-he disc 54 being in the path of flux fromthe electromagnet 55, would act, if stationary, as a short circuitedwinding of a transformer in which the coil 56 of the electromagnet wouldthen be the primary. a

Acting as such a short circuited secondary winding of a transformer, thedisc 59 would merely change the effective impedance of the transformercircuit and since the disc 54 is of uniform resistance, its rotationwill not change the eiective impedance of the transformer circuit fromwhatever its value would be if stationary. The action when the discrotates may be likened to that of a series dynamo, since the value ofthe current generated in the disc caused by its motion is proportionalto its speed and the magmtude of the flux. The magnitude of the flux isin turn proportional to the speed of the generator, so that .the currentgenerated in the disc is proportional to the square of the speed of themoving system. The magnetic effect of these currents would be oppositeto that of the magnet coil on one side and in the same direction on theother side, thus tending to distort 4the flow of flux from the poles.This may or may not affect the current flowing in the magnet coil 56,but whatever effect it may have is proportional to the magnitude of thecurrent generated in the disc by reason of its motion, and this isproportional to the square of the speed.

The counter torque due to these various losses above enumerated appearsto vary then as a whole, with some function of the speed, greater thanthe first power but not as large as the square.

Referring now to the previously described compensating means 85-89 whichcompensate for these losses, it will be evident that under conditions offlow within the conduit Il there will be a pressure differentialbetweenl opposite sides of the diaphragm plate 93 which will be afunction of the Velocity of the gas. Assuming for the moment that thespring pressed valve 9| is locked at one xed size of opening, thepressure differential across the diaphragm plate will then beproportional to the square of the gas velocity. The pressuredifferential will maintain a fiow of gas from the upstream side ofdiaphragm plate 93 through pipe 81, valve 89 and the synchronous motor41.

this gas flow will be conducted through pipe 88 back to the downstreamside of the diaphragm plate 93. In issuing from the nozzle 86, this gasow Vwill strike the impulse vanes of impulse' wheel 85 and create atorque on the rotary member m. The arrangement is such that thedirection of this torque is the same as that caused by this compensatingtorque will be proportional to the product of .the density of the gasand the square of the velocity of the gas issuing from the nozzle 86.With a givenI setting of valve 89, this nozzle velocity will beproportional to the square root of the differential pressure existingbetween pipes 81 and 88 at their points of connection to conduitsections Il and IIb.. Assuming, as above stated, that .the springpressed valve 9| were to remain in fixed position, so .that the port 92would then function as a fixed orifice, the pressure differential whichwould then be maintained in the pipes 81 and 88 would be proportional tothe square of the gas velocity, which would mean that the velocity ofthe gas issuing from the nozzle 86 would then be proportional to thevelocity of the gas in the conduit Il, or proportional to the speed ofrotary member m. However, this differential pressure is not proportionalto the square of the velocity of the gas in the conduit il and thisnozzle velocity is not proportional to the velocity of the gas inconduit Il by reason of the fact ythat the position of the springpressed valve 9|. Ovaries with changes of velocity and hence the port 92is not a fixed orifice. The-effective size of this port or orificebecomes larger as the pressure differential increases, inasmuch as thisdiierential pressure acts on the valve 9| and pushes it back away fromthe port 92 against the action of the spring 99. The differentialpressure is therefore no longer proportional toy the square of thevelocity of the gas in conduit Il, but becomes some lesser function ofthe velocity, depending upon 'the adjusted pressure of the spring 99.

It will be seen from the foregoing that by properly calibrating thepressure of the spring 99 and that by properly adjusting theeffectivearea of opening through the valve 89, a compensating torque can beestablished in the impulse wheel 85 which will entirely or very closelycompensate for the loss of torque on the vanes I1 and for the dragtorque which arises from the various factors specifically enumeratedabove. Hence, by applying this compensating torque to the shaft m, thespeed of this shaft can then be made truly proportional to the velocityor to the product of velocity and density, whichever may be desired.

Referring particularly to the fact that in the embodiment of myinvention illustrated in Figure 1 there is no mechanical transmission ofmotion from the impact wheel I6 to the integrating The magnitude of vcounter d5, but, instead, the motion is transmitted electrically, suchelectrical transmission has certain obvious advantages in differenttypes of installations where it may be desired to locate the integratingcounter l5 at some distancev from the gas conduit Il. Such electricaltransmission of motion also has the added advantage of enabling theimpact wheel I6 to be mounted inv one gas-tight housing, and thecompensating impulse wheel 85 to be mounted in a separate gastighthousing, so that the compensating flow of gas impinging against thelatter wheel 85 can possibly be calibrated more easily, independently ofthe gas entering the housing l5 through the impact Wheel I6.

impact wheel slot I9. However, where. location of the integratingcounter 45 at a remote point is not essential, it is entirelypracticable to employ a mechanical drive from the impact wheel I6 tosuch integrating counter, as I shall presently describe in connectionwith Figure 4. Before describing this mechanical transmissionarrangement, it is appropriate to point out that the electricaltransmission disclosed in Figure 1 can be accomplished by differenttypes 'of electrical apparatus. For example, although a three phasesystem is preferable from the standpoint-f the starting characteristicof the motor 41 and of effective synchronized coupling between thealternator unit 21 and the motor unit 41, nevertheless these two unitsmight be two phase, quarter phase or even single phaseunits. stance, themotor 41 should be self-starting, but thisvis common practice even insingle phase units, as represented by self-starting, single phase clockmotors. Furthermore, the self-starting requirement is not an acuteproblem ln the present flow meter, because from a condition of rest theimpact wheel I6 will come up to speed rather gradually, and this enablesthe motor unit 41 to come into concurrent operation more readily. Undersome operating conditions, the motor unit 41 might be an inductionmotor, a repulsioninduction motor, a split-phase motor or any othersuitable type of motor. Also, under some conditions, a direct currenttransmission system might be employed, in which case the motor unit 41would preferably be appropriately compounded to closely approximate thedesired speed-voltage characteristic. In any single phase alternatingcurrent system, the branch circuit which energizes the electromagnetcoil 56 and the branch circuit which energizes the remote indicatingdevices |01 and |08, could both be tapped off the single phasetransmission circuit, or a separate single phase winding could beprovided in the alternator 21 for energizing such branch circuits. Inthe case of a direct current system, the electromagnet coil 56 would beenergized by this direct current through its branch Acircuitsubstantially in the same manner previously described, but the remoteindicating devices |0I, |01 and |08 would have to respond to voltage.

In the embodiment illustrated in Figure 4 I have disclosed a directcoupled arrangement in which the torque transmitting relation betweenthe impact wheel I6, integrating counter 45 and retarding disc 54 is byvirtue of a mechanical driverather than by an electrical drive. In thisembodiment, all of the rotating parts can be enclosed within a singlehousing III. Also, all of Vthe rotating parts consisting'of the impactwheel I6, the generator 21, the integrating counter 45 and the retardingdisc 54 all have mechanical connection with a single rotary member m1,the integrating counter 45 having an appropriate geared connection withsaid shaft m1 for securing the proper speed reductionwith respect to theThe ends of the shaft m1 have appropriate mounting in bearings ||2carried by the end walls of the housing III. In this direct coupledembodiment, the generator 21 serves only l 21 can therefore be analternating current generator, such as the single phase alternatorshown,

, or it can be a direct ciurent generator, either type of current beingadequate for the controlled In each inenerglzation of the winding 56.Where an accurate indication by lthe remote indicators I0 I, |01 and |08is desired, the use of alternating current is preferable to the use ofdirect current. Where it is desired that the indication be proportionalfvice 58 in which the current ow 'is made to vary as a function of thedensity of the gas, as described of the device 58 in the embodiment ofFigure l. Where it is desired to measure actual volume at flowingconditions independently of density changes, the reversed arrangement ofdensity responsive device 58' illustrated in Figure 3 would be employed.A

In this-direct coupled embodiment, the loss compensating means ismotivated by the gas which enters the housing III through the slot I9extending betweenfsaid housing and the conduit II. A partition |I4divides the housing III into upperv and lower chamber areas |I and I I6.Extending through this partition is a circular passageway I I1, andmounted on the shaft m1, within this passageway II1, is a suitable vaneor impulse wheel II8. A pipe 88I conducts gas from preceding embodiment.Thus, a pressure diierential is maintained for establishing a iiow ofgas past the impulse wheel I I8, and the volume of this flow can beaccurately regulated by the needle valve 89 interposed in the pipe 88,substantially as described of the gas flow effective on the impulsewheel 85 of the preceding embodiment.

This direct connected embodiment of flow meter has the same mode ofoperation as the embodiment illustrated in Figure l, and the samemathematical proof of accuracy is also applicable to this direct coupledembodiment.

The impact energy of the gas iiow may be converted into rotary motion byvarious other arrangements of fans, propellers, impulse wheels,A

etc., as illustrated infFigures 5, 6 and 7. In Figure 5 an impulse wheel|2I in the nature of a turbine wheel is substituted for the vane rotorI6 of the preceding embodiments. This impulse wheel is enclosed ina'housingll22 through which the flow of gas passes. The stream of thegas enters the housing through a nozzle |23 which directs the gassubstantially tangentially against the multiple vanes of the impulsewheel I2I, and the gas leaves the housing -through the outlet connection|24. The shaft or rotary member m2 driven by the impulse wheeldrives thegenerator 21. This form of the invention using such impulse wheel isparticularly adapted to low capacity meters Where the entire ow of gascan readily be led through a housing and a comparatively small nozzle orpipe. This form of the invention utilizing such impulse wheel can beemployed either in the electrically coupled embodiment ofthe inventionillustrated in Figure l, or in the mechanically coupled embodiment ofthe invention illustrated in Figure 4.

Figure 64 diagrammatically illustrates the use of a fan or propellertype of impact wheel |21 which is disposed substantially axially withinthe gas conduit I I. This fan or propeller isl mounted directly on theshaft m3 of the generator 21,

and the latter is supported within the conduit by a suitablespiderstructure I 28. This arrangelio n illustrated in Figure 4.

Figure 7 diagrammatically illustrates the useA of an axial or sideadmission type of turbine wheel |3I. The latter is enclosed in a housing|32, and the entering gas is discharged through a nozzle |33 laterallyagainst the multiple vanes of the wheel, the gas being discharged fromthe housing through the outlet connection |34. The shaftI or rotarymember m4 drives the generator 2l. This form of the invention can alsobe employed in connection with either the electrically coupledembodiment illustrated in Figure 1 or with the mechanically coupledembodiment illustrated in Figure 4.

Any one of the impact Wheels illustrated in Figures 5, 6 and 7 may besubstituted for either of the compensating Wheels 85 and l I8illustrated in Figures 1 and 4, if desired.'

While I have illustrated and described what I regard to be the preferredembodiments of my invention, nevertheless it will be understood thatsuch are merely exemplary, and' that numerous modifications andrearrangements may be made therein without departing from the essence ofthe invention. For example, if it is desired to give an indication whichis independent of changes of density of the gas in any of theembodiments of the invention, the functioning of the density sensingdevice 58 or 58 "can be switched or cut out of the control circuit 35,36, such as by the switch indicated in dotted lines at |36 in Figurefl,so that the current supplied by the generator 21 is fed directly to thewinding 56 independently of any changes in the effective resistance ofresistor 82 or 821'.

I claim:

1. In a flow meter of the class described, the combination of a rotarymember, means respon- -sive to fluid flow for rotating said member,indicating means actuated by said rotary member, and means for imposinga counter torque on said rotary member which is proportional to theproduct of the square of the speed of the flow responsive m eans and thereciprocal of the density of the fluid.

2. In a flow meter ofthe class described, the combination of a rotarymember, a wheel rotated by the kinetic energy of the fluid flow andarranged for imparting driving torque to said rotary member, integratingmeans actuated by said rotary member, means for creating a countertorque in said rotary member which is varied by changes in the Velocityand density of the fluid, and means for creating an accelerating torquein said rotary member which is varied by changes in the velocity of thefluid.

3. In a flow meter for gaseous fiuids, the combination of an impactwheel responsive to the kinetic energy of the fluid flow, a generatordriven by said impact Wheel, integrating means driven by said impactwheel, electromagnetic means creating a counter torque for governing thespeed of rotation of said integrating means, said electromagnetic meanscomprising a Winding energized by current flow from said generator,

a buoyancy element responsive to the density of the gaseous fluid, andmeans responsive to said buoyancy element for varying said current flow.

4. In a meter for measuring the fiow of gaseous fluids through aconduit, the combination of an impact wheel revolved by the kineticenergy of the fluid flow through said/conduit, an alternator driven bysaid impact Wheel, a closed chamber, a rotary member mounted in saidchamber, an electric motor having synchronous characteristics Areceivingalternating current from said alternator and connected to drive saidrotary member, integrating means driven by said rotary member, apparatusfor producing a counter torque in said rotary member comprising aWinding for establishing a magnetic field, and

a short circuited conductor driven -by said rotary member for cuttingsaid field, a circuit for conducting current 'from said alternator tosaid winding, a buoyancy element adapted to have motion in response tochanges of density in the gaseous fluid, variable resistance meansactuated by said buoyancy element for varying the current flow in saidcircuit, a compensating wheel within said closed chamber adapted toimpart accelerating torque to said rotary member, a fluid -bypass forconducting fluid from said conduit to said closed chamber for reactingagainst said compensating Wheel and for returning the gas from saidchamber to said conduit, and a spring pressed valve in said conduit forestablishing a pressure differential between the inlet and outlet`endsof said fluid bypass.

5. In a meter for measuring the oW of gaseous uids through a conduit,the combination of an impact wheel driven by the fluid flow through saidconduit, a closed chamber communicating with said conduit to receivefiuid therefrom, a

'rotary member in said chamber mechanically coupled with said impactwheel to be driven thereby, integrating means driven by said rotarymember, a generator driven by said rotary member, apparatus forestablishing a counter torque in said rotary member comprising a Windingfor creating a magnetic eld, and a short circuited conductor rotatingwith said rotary member and adapted to cut said field, a circuit forconducting current from said generator to said winding, a buoyancyelement adapted to have motion in response to changes of density in thefluid flowing through saidy conduit, variable resistance means actuatedby said buoyancy element for varying the current flowing through saidcircuit, a pipe for conducting gas from said closed chamber back to saidconduit, means establishing an `orifice in said conduit which varies ineffective area with changes of velocity of the fluid, said variableorifice creating a pressure differential vanes being shapedsubstantially as sectors of' the conduit area.

` EDWARD L. FISCHER.

